1. Field of the Invention
The present invention relates to a roller device for use in a conveyor or the like apparatus, and more particularly relates to the roller device whose characteristic feature resides in a structure of securing to a roller body a fixture that is accommodated therein wholly or partially.
2. Related Art
Various types of free rollers and/or motored rollers have been employed to construct the conventional conveyors or the like apparatuses. Each free roller has comprised a roller body formed as a round cylinder supported by and rotating about a shaft, and each motored roller has comprised a motor and a reducer both installed in the roller body.
In these free rollers and motored rollers, fixtures or closures for closing end openings of each roller body, as well as bearings or other constituent parts, have been fixed on or in the roller body. Usually, adhesives, set-screws, grooved pins, spring pins or the like fastening members have been used to rigidly secure such fixtures or parts to said roller body.
An example of the prior art structures is disclosed in the Japan Patent Laying-Open Gazette No. 6-171730. In this case, a fixing ring intervenes between the roller body and a closure as the fixture closing the open end thereof. A set-screw will be tightened sideways through a cap in order to firmly secure the fixture to the roller body in a wedge-like manner.
Another prior art example disclosed in the Japan Patent Re-Laying-Open Gazette No. 56-500610 proposes an annular groove to be formed in and around the closure. A circular edge of the roller body will be folded back to fit in the annular groove so as to retain the closure.
Arrays of these free rollers and/or motorized rollers are often used to transport any articles, goods or materials, suffering from mechanical vibration and shocks while they are transporting the articles. It has been observed often that holes or apertures for insertion of those set-screws or pins would possibly be widened gradually, loosening them and causing them to slip off at worst. In such an event, the roller bodies would no longer rotate smoothly, thus failing to transport the goods in an orderly manner.
If such set-screws or the like threaded fasteners are used for the described purpose, then those roller bodies and fixtures must be threaded not easily. Chip that is a metal powder or dust produced when machining such fasteners, is likely to undesirably stick to the surface of said roller body and often stray into it.
A relatively complicated structure for securing the fixture such as a closure to the roller body as proposed in the Gazette No. 6-171730 or No. 56-500610 will render its assembling works very intricate to raise manufacture cost.
An object of the present invention is to provide such a roller device that its fixture such as a closure or bearing is easily secured on its roller body with use of a fastening member, lest any vibration or other mechanical stress transmitted or imparted to the roller device should cause the fastening member to slip off.
A roller device provided herein to achieve this object may comprise a roller body, a fixture accommodated at least in part in the roller body to be secured thereto, and at least one punched hook-engagement that is formed in and between an inner periphery of the roller body and an outer periphery of the fixture. The punched hook-engagement may be produced in such a manner that the peripheries overlying one another are brought into close contact with each other at least in part so that portions of said peripheries are struck inwardly and radially of the roller body so as to cause permanent and integral plastic deformation of the said portions.
In each punched hook-engagement, such a plastically deformed portion of the roller periphery fits in that of the fixture. These deformed portions firmly hook one another, so that the fixture is prevented from moving relative to the roller body not only in circumferential but also in axial direction thereof. Thus, it is a matter of course that the fixture held in place in this fashion is protected from slipping off.
Any set-screws or set-pins need not be used in the roller device of the invention to fasten the fixture to the roller body, making it unnecessary to prepare any apertures for those screws or the like during manufacture of the roller device. Manufacture process is thus simplified, with the number of constituent parts being reduced to lower manufacture cost.
The fixture may have at least one cavity extending axially so as to be located near the periphery thereof. Each of the plastically deformed portions constituting the punched hook-engagement may project partially or wholly into this cavity.
From another aspect of the invention, it provides a roller device comprising a roller body, a fixture accommodated at least in part in the roller body to be secured thereto, and at least one punched hook-engagement that is formed in and between an inner periphery of the roller body and an outer periphery of the fixture. The fixture may have at least one cavity extending axially inwards so as to be located near the periphery thereof. The punched hook-engagement may be produced in such a manner that the peripheries over-lying one another are brought into close contact with each other at least in part so that portions of said peripheries are struck inwardly and radially of the roller body so as to cause permanent and integral plastic deformation of the said portions, in such a fashion that each plastically deformed portion constituting the punched hook-engagement may project partially or wholly into the cavity.
Certain peripheral areas of the roller body and fixture closely inserted therein will overly and surround the cavity to be easy and ready to make plastic deformation in unison and in harmony with each other, in response to a shock or the like external force applied from the outside onto the roller body.
The cavity extending axially inwards a distance from the end face of the fixture may also extend a length tangentially thereof so as to have an elongate opening in the said face.
There is a possibility that a target point for the shock would erroneously be located slightly offset with respect to the center of cavity, circumferentially or longitudinally of the roller body, due to the cylindrical shape thereof. However, such a cavity extending or elongated in both the tangential and axial directions does ensure inward projection of the punched hook-engagement, thereby affording a reliable consolidation of the roller body and fixture.
Preferably, the number of punched hook-engagements serving as fasteners is two or more arranged at angular intervals around the roller body.
Such deformed portions as the fasteners arranged around the roller body need only to withstand distributed portions of any angular vibration imparted to this roller device. The fixture will thus be prevented well from moving relative to the roller body not only in circumferential but also in axial direction thereof. It is a matter of course that the fixture held in place in this fashion is protected from slipping off.
Each punched hook-engagement may assume a generally rectangular recess, in its outer appearance, that preferably has axial sides and tangential sides.
In this case, such axial sides inhibit the fixture from making any angular displacement relative to the roller body, with the tangential sides inhibiting the fixture from being displaced longitudinally of said roller body.
Preferably, the roller body may have a smooth inner peripheral surface and the fixture has a smooth outer peripheral surface, such that they have no irregularities such as corrugations, recesses, lugs or dimples. Surface areas of the inner and outer peripheries subject to the process of making the punched hook-engagements will be held in a close and tight contact with each other.
In such a case, any intentional irregularity need not be preformed in those peripheries prior to assembling the roller device, thus simplifying and economizing the manufacture process.
The roller device may comprise an electric motor installed in the roller body to be driven by it.
Although the motor generates and transmits vibration to the roller body and fixture, they who are consolidated in the described manner will neither displace themselves tangentially or axially, nor causing the fixture to slip off to hinder smooth rotation of the roller body.
Also preferably, the fixture may be formed of a material softer than that used to form the roller body.
An inward external force for plastically deforming them will be attenuated by the outer roller body, but remaining strong enough to deform such a softer inner fixture. Thus, a weaker force will suffice well to plastically produce the described punched hook-engagement.
From a still another aspect, the present invention will provide a method of making a roller device comprises a roller body, a fixture accommodated at least in part in the roller body to be secured thereto, and at least one punched hook-engagement that is formed in and between an inner periphery of the roller body and an outer periphery of the fixture. The method of the present invention comprises the steps of preliminarily inserting the fixture into the roller body so as to cause it to take a predetermined position in this body where the peripheries have their areas aligned and kept in contact with each other, and subsequently applying an external force inwardly in a radial direction onto the aligned areas so as to deform said areas in unison to form the punched hook-engagement.
In the punched hook-engagement produced in this way, a deformed fragment or fragments of such an area of the roller body periphery is or are fitted in that or those of the area of said fixture periphery. Thus, the fixture is rigidly united with the roller body to construct the roller device, that is free from displacement between the fixture and roller body and also free from the slipping-off of said fixture even if subjected to vibration.
Any set-screws or set-pins need no longer be used in manufacturing the roller device whose fixture is firmly adjoined to the roller body, making it unnecessary to prepare any apertures for those screws or the like during manufacture of the roller device. Manufacture process is thus simplified, with the number of constituent parts being reduced to lower manufacture cost.
The fixture used in the present method may have at least one cavity located near the periphery thereof. Each of the plastically de-formed portions constituting the punched hook-engagement may project partially or wholly into this cavity.
Certain peripheral areas of the roller body and fixture closely inserted therein in the present method will overlay and surround the cavity to be easy and ready to make plastic deformation in unison and in harmony with each other, in response to a shock or the like external force applied from the outside onto the roller body.
The cavity or cavities formed in the present method to extend axially inwards a distance from the outer end face of the fixture may also extend a proper length tangentially thereof so as to have an elongate opening in the said face.
There is a possibility that a target point for the shock would erroneously be located slightly offset with respect to the center of cavity, circumferentially or longitudinally of the roller body, due to the cylindrical shape thereof. However, such a cavity extending or elongated in both the tangential and axial directions does ensure inward projection of the punched hook-engagement, thereby affording a reliable consolidation of the roller body and fixture.
Preferably, the number of punched hook-engagements is two or more arranged at angular intervals around the roller body.
Such deformed portions as the fasteners arranged around the roller body in the present method need only to withstand distributed portions of any angular vibration imparted to this roller device. The fixture will thus be prevented well from moving relative to the roller body not only in circumferential but also in axial direction thereof. It is a matter of course that the fixture held in place in this fashion is protected from slipping off.
Each punched hook-engagement may assume a recess, in its outer appearance, that preferably has axial sides and tangential sides.
In this case, such axial sides employed in the present method inhibit the fixture from making any angular displacement relative to the roller body. The tangential sides likewise inhibit the fixture from being displaced longitudinally of said roller body, thus affording a much surer consolidation of the roller body and fixture.
Preferably, the roller body may have a smooth inner peripheral surface and the fixture has a smooth outer peripheral surface, such that they are free of any irregularities such as corrugations, recesses, lugs or dimples. Surface areas of the inner and outer peripheries will be subjected to the step of inserting the fixture so that they remain held in a close and tight contact with each other while being processed at the step of applying the external force to produce the punched hook-engagements.
In such a mode of the present method, any intentional irregularity need not be preformed in those peripheries prior to assembling the roller device, thus simplifying and economizing the manufacture process.